Rifamycin sv derivatives

ABSTRACT

The application discloses new rifamycin SV derivatives in which a sulfur atom links the rifamycin nucleus to radicals of various nature. A process for the preparation of the new derivatives, which show a high degree of antibacterial activity, is also disclosed.

United States Patent Inventor Nicola Maggi Milan, Italy App1.No. 675,341

Filed Oct. 16, 1967 Patented Dec. 7, 1971 Assignee Lepetit S.p.A.-Gruppo per la Ricerca Scientiiica e la Produzione Chimica Farmaceutica Milan, Italy Priority Oct. 25, 1966 Great Britain 47,899/66 RIFAMYCIN SV DERIVATIVES 7 Claims, No Drawings US. Cl 260/239.3, 424/244, 424/285, 424/274, 424/273 Int. Cl C07d 87/54 Field of Search 260/2393 OTHER REFERENCES Fieser and Fieser, Organic Chemistry," 3rd Ed., pp. 716- 719 (Reinhold) (1956) Primary Examiner-Henry R. .liles Assistant Examiner- Robert T. Bond AtI0rneyJ0seph l-lirschmann ABSTRACT: The application discloses; new rifamycin SV derivatives in which a sulfur atom links the rifamycin nucleus to radicals of various nature. A process for the preparation of the new derivatives, which show a high degree of antibacterial activity, is also disclosed.

RIFAMYCIN SV DERIVATIVES The present invention concerns new derivatives of rifamycin SV wherein at position 3 a sulfur atom links the rifamycin nucleus to radicals of various kind. The general formula of the new compounds if the following wherein R is a member of the class consisting of carboxyalkyl, aminoalkyl, di-lower alkylaminoalkyl, benzimidazolylethyl, 2- acetamidoethyl, pyrrolidinomethyl, Z-(carboxymethylcarbamyl)-2-(y-amino-ycarboxypropionamido)-ethyl, guanidinoethyl groups.

The process for preparing this class of new compounds comprises the step of contacting rifamycin S with 1-2,5 equimolecular amounts of the selected compound containing a -SH group in its molecular structure, in an aqueous organic solvent. The mixture is allowed to react under stirring for 20-120 minutes in relation to the more or less marked reactivity of the reagent. Purification is accomplished by conventional routes.

The mechanism of the reaction consists in the addition of the thiol group to the rifamycin S, and in the simultaneous reduction of the quinone group contained in the rifamycin S molecule to hydroquinone. The process can therefore be represented by the following equation:

Me Me The chemical and physical properties of this class of compounds are in close connection with the ones of the family of rifamycins, and in particular rifamycin SV; these compounds are soluble in neutral oralkaline solutions.

The whole class of compounds shows a marked antibiotic activity especially against gram-positive bacteria. In the following table the minimal inhibitory concentration and the ED of some compounds are given.

Mlnilnal inhibitory concentration in vitro, pg/ml. against- M. St.hemol. tuberculosis The following nonlimitative examples illustrate the invention.

EXAMPLE 1 Preparation of 3-glutathionyl-rifamycin SV An amount of 3.5 g. (0.005 moles) of rifamycin S is dissolved in 50 ml. of tetrahydrofuran. This solution is cooled to 4-5 C. then a solution of 1.85 ml. (0.006 moles) of reduced glutathione dissolved. in 25 ml. of water is added under stirring, which is prolonged for about 2 hours at 5 C. About 250ml. of water are then added, and the mixture is extracted twice with ethyl acetate to remove some small traces of rifamycin S and SV; then aqueous 10 percent hydrochloric acid is added (up to pl-1=2) and an extraction with butanol is carried out. The organic layer is concentrated in vacuo to 10 ml.; this solution is poured into 200 ml. of ligroin whereby a orangeyellow precipitate is formed. This is thencollected on a filter. washed with ligroin and dried. it is then chromatographically purified on columns by solution in water made slightly alkaline (p1-1=7.5), and using water as the eluting solvent. The eluate is recovered, aqueous 3 percent ascorbic acid is added, the pH is adjusted to 2. An extraction is made with butanol and the organic layer, after concentration in vacuo, is poured into ligroin: the clear yellow precipitate is collected, washed with ligroin and dried in vacuo. Yield 2.4 g. (48 percent) of 3-glutathionyl-rifamycin SV (C H MO S) decomp. point 162 0.; A max 320 and 450 ,1.

EXAMPLE 2 Preparation of 3-(B-aminoethyl)-tlhio-rit amycin SV To a stirred and cooled (24C.) solution of 2.4 g. (0.021 moles) of mercaptoethylamine hydrochloride in 35 m1. of aqueous 10 percent tetra-hydrofuran, acooled solution of 7 g.

(0.01 moles) of rifamycin S and 2.8 in]? 0.02 moles) of EXAMPLES 3-8 The following compounds were prepared as described in example 2. The reaction time and temperature are given.

wherein R is a member of the class consisting of carboxylower alkyl, amino-lower alkyl, di-lower alkylamino-lower albenzimidazolylethyl,

kyl,

rolidinomethyl,

at position 3 of rifamycin SV is N 8 CHr-CHz- 20 10 152-155 325 and 455.

3. A compound as in claim 1, wherein the group substituted at position 3 of rifamycin SV isthe Z-aminoethyl group.

44 A compound as in claim 1, wherein the group substituted at position 3 of rifamycin SV is the Z-dimethylaminoethyl 5. A compound as in claim 1, wherein the group substituted at position of r i fam ycin S V is the Z-guanidinoethyl group.

6. A compound asin claim 1 wherein R is Z-acetamidoethyl.

7. A compound as in claim 1 wherein R is pyr- 9 CHzCHgN(CH3)2 6 180-182 320 and 450.

We claim: 1. A compound of the formula l\|'[e Me 1? HO H 0 ton Me I 4 ,5 P M80000 H 0 Me Me OH OH I g NH rolidinomethyl.

Me .M

O ONHCHQOOOH Nnoocmompnc OOH Z-acetamidoethyl. 2-(carboxymethylcarbamyl)-2(y-amino--y- 5 carboxypropionamido)-ethyl and guanidinoethyl groups.

2. A compound as in claim 1, wherein the group substituted 

2. A compound as in claim 1, wherein the group substituted at position 3 of rifamycin SV is
 3. A compound as in claim 1, wherein the group substituted at position 3 of rifamycin SV is the 2-aminoethyl group.
 4. A compound as in claim 1, wherein the group substituted at position 3 of rifamycin SV is the 2-dimethylaminoethyl group.
 5. A compound as in claim 1, wherein the group substituted at position 3 of rifamycin SV is the 2-guanidinoethyl group.
 6. A compound as in claim 1 wherein R is 2-acetamidoethyl.
 7. A compound as in claim 1 wherein R is pyrrolidinomethyl. 